# What is difference between critical points and inflection points?

critical point of $f$ = critical number for $f$ = value of $x$ (the independent variable) that is 1) in the domain of $f$, where $f '$ is either $0$ or does not exists. (Values of $x$ that meet the conditions of Fermat's Theorem.)
An inflection point for $f$ is a point on the graph (has both $x$ and $y$ coordinates) at which the concavity changes.